The present invention relates generally to operations performed and equipment utilized in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a surface controlled subsurface lateral branch safety valve and associated systems and methods.
In some jurisdictions, commingling production from different reservoirs is allowed. This is flow from each of multiple branch wellbores into a common main or parent wellbore extending to the surface. It is appreciated by those skilled in the art that this is a difficult task, and yet several systems have been proposed for complying with this requirement. Unfortunately, each of these proposed systems suffers from at least one major drawback.
One system uses a completion string installed in the main wellbore. The completion string includes a flow control device, such as a valve or choke, for each branch wellbore. Packers are interconnected in the completion string between the flow control devices to isolate the branch wellbores from each other. The flow control devices are positioned opposite their respective branch wellbores, and the flow control devices are used to regulate flow from the individual branch wellbores into the completion string.
This system restricts the area available for production to the inner diameter of the completion string. In addition, this system prevents access to the branch wellbores. To provide access to a branch wellbore, the completion string must be pulled out of the main wellbore, which is very costly and time-consuming.
In another system, a flow control device is positioned in each one of multiple branch wellbores. The flow control devices are controlled by use of cables, control lines, power lines, etc., extending into each branch wellbore from the main wellbore. Alternatively, the flow control devices may be battery-powered and/or may be remotely controlled via telemetry.
This system has the disadvantage that the flow control devices must be positioned in the branch wellbores, where they are difficult to access for maintenance, etc. In addition, the version having cables, lines, etc. extending in the main and branch wellbores has the disadvantages of restricting access through the wellbores, the possibility of damage to the lines and cables, the difficulty of installing the flow control devices, lines and cables, etc. If the flow control devices are battery-powered, the need to periodically replace or recharge the batteries increases the disadvantage of difficult access to the flow control devices in the branch wellbores.
Therefore, it is known to those skilled in the art that an improved system and method of controlling flow between branch and main wellbores is needed.